D-Link DES-3226L, Справочник команд интерфейса командной строки

Страница: 127 / 128

Glossary 127
the network layer in addition to the physical layer. This
allows administrators to analyze traffic by protocol.
RP. Rendezvous Point. Used with IP Multicast.
RPF. Reverse Path Forwarding is the fundamental
concept in multicast routing that enables routers to
correctly forward multicast messages down the
distribution tree.
RPU. Remote Power Unit.
RTOS. See “Real-Time Operating System” on page 126.
S
SDL. Synchronous Data Link.
Simple Network Management Protocol. SNMP is the
protocol governing network management and the
monitoring of network devices and their functions. It is not
necessarily limited to TCP/IP networks. The versions have
the following differences:
SNMPv1 (full): Security is based on community strings.
SNMPsec (historic): Security is based on parties. Few, if
any, vendors implemented this version of the protocol,
which is now largely forgotten.
SNMPv2p (historic): For this version, much work was
done to update the SNMPv1 protocol and the SMIv1, and
not just security. The result was updated protocol
operations, new protocol operations and data types, and
party-based security from SNMPsec.
SNMPv2c (experimental): This version of the protocol is
called community string-based SNMPv2. It is an update of
the protocol operations and data types of SNMPv2p, and
uses community-based security from SNMPv1.
SNMPv2u (experimental): This version of the protocol
uses the protocol operations and data types of SNMPv2c
and security based on users.
SNMPv2* (experimental): This version combined the best
features of SNMPv2p and SNMPv2u. (It is also called
SNMPv2star.) The documents defing this version were
never published as RFCs.
SNMPv3 (proposed): This version of the protocol is a
combination of user-based security and the protocol
operations and data types from SNMPv2p and support for
proxies. The security is based on that found in SNMPv2u
and SNMPv2*, and updated after much review. The
documents defing this protocol will soon be published as
RFCs.
. SNMP. See “Simple Network Management Protocol” on
page 127.
SODIMM. Small Outline Dual Inline Memory Module.
SRAM. Static Random Access Memory.
STP. Spanning Tree Protocol. See “802.1D” on page 123
for more information.
SVL. Most switches support Independent learning,
wherein traffic from one VLAN will not be forwarded to
another VLAN. Hence if some limited form of forwarding
needs to be supported, the switch should implement
Shared VLAN learning.
T
TBI. Ten Bit Interface.
Telnet. A character-based UNIX application that enables
users with a Telnet server account to log on to a UNIX
computer and utilize its resources.
TFTP. See “Trivial File Transfer Protocol” on page 127.
Trivial File Transfer Protocol. TFTP is a simple form of
the File Transfer Protocol (FTP). TFTP uses the User
Datagram Protocol (UDP, a direct protocol used to
communicate datagrams over a network with little error
recovery) and provides no security features. It is often
used by servers to boot diskless workstations, X-terminals,
and routers.
Trunking. The process of combing a set of trunks that are
traffic-engineered as a unit for the establishment of
connections between switching systems in which all of the
communications paths are interchangeable.
V
Virtual Local Area Network. Operating at the Data Link
Layer (Layer 2 of the OSI model), the VLAN is a means
of parsing a single network into logical user groups or
organizations, as if they physically resided on a dedicated
LAN segment of their own. In reality, this virtually
defined community may have individual members
peppered across a large, extended LAN. The VLAN
identifier is part of the 802.1Q tag, which is added to an
Ethernet frame by an 802.1Q-compliant switch or router.
Devices recognizing 802.1Q-tagged frames maintain
appropriate tables to track VLANs. The first three bits of
the 802.1Q tag are used by 802.1P to establish priority for
the packet.
VLAN. See “Virtual Local Area Network” on page 127.